Sam, the year before last a similar thing happened to me. We were out at a club on my Birthday and a guy started on me saying that I kicked him (I hadn't). Hubby stepped in to tell the lad to calm down and that he'd made a mistake, but a group of about 7 people dived on him and others pinned me back against the wall. When they let me go I couldn't find hubby, he got up off the floor with his head p*ssing with blood. He had to have stiches half a cm under his eye, on his head and gluing the back of his head and spending the rest of the week looking like Shrek and being unable to eat due to the massive footprint down the side of his head and jaw where they were jumping on him with boots on.
My husband has practised Ju Jitsu for 7 years, but when it is a surprise attack of 7 against one you don't really stand a chance.
Although the police gave us a lift home from the hospital we didn't follow it through as we knew nothing would happen.
Also, during a house party last Summer the guy who started the whole incident was stabbed in the head.